three/src/nodes/core/AttributeNode.js

JavaScript 3D library

import Node from './Node.js';
import { varying } from '../tsl/TSLBase.js';
import { warn } from '../../utils.js';

/**
 * Base class for representing shader attributes as nodes.
 *
 * @augments Node
 */
class AttributeNode extends Node {

	static get type() {

		return 'AttributeNode';

	}

	/**
	 * Constructs a new attribute node.
	 *
	 * @param {string} attributeName - The name of the attribute.
	 * @param {?string} nodeType - The node type.
	 */
	constructor( attributeName, nodeType = null ) {

		super( nodeType );

		/**
		 * `AttributeNode` sets this property to `true` by default.
		 *
		 * @type {boolean}
		 * @default true
		 */
		this.global = true;

		this._attributeName = attributeName;

	}

	isCacheable( /*builder*/ ) {

		return false;

	}

	getHash( builder ) {

		return this.getAttributeName( builder );

	}

	/**
	 * Returns the node which provides the value of this attribute in the current context, if any.
	 * The context can provide attributes with a `getAttribute( name, builder )` function, e.g. if the
	 * vertices are pulled from a storage buffer or the surface is reconstructed per fragment. The
	 * function should return the same node for the same attribute.
	 *
	 * @param {NodeBuilder} builder - The current node builder.
	 * @return {?Node} The node providing the value of the attribute.
	 */
	getContextAttribute( builder ) {

		const getAttribute = builder.context.getAttribute;

		return getAttribute ? getAttribute( this.getAttributeName( builder ), builder ) : null;

	}

	/**
	 * An attribute provided by the context is replaced by the provided node, like an override.
	 *
	 * @param {NodeBuilder} builder - The current node builder.
	 * @return {Node} The shared node if possible. Otherwise `this` is returned.
	 */
	getShared( builder ) {

		return this.getContextAttribute( builder ) || super.getShared( builder );

	}

	generateNodeType( builder ) {

		const contextAttribute = this.getContextAttribute( builder );

		if ( contextAttribute ) return contextAttribute.getNodeType( builder );

		let nodeType = this.nodeType;

		if ( nodeType === null ) {

			const attributeName = this.getAttributeName( builder );

			if ( builder.hasGeometryAttribute( attributeName ) ) {

				const attribute = builder.geometry.getAttribute( attributeName );

				nodeType = builder.getTypeFromAttribute( attribute );

			} else {

				nodeType = 'float';

			}

		}

		return nodeType;

	}

	/**
	 * Sets the attribute name to the given value. The method can be
	 * overwritten in derived classes if the final name must be computed
	 * analytically.
	 *
	 * @param {string} attributeName - The name of the attribute.
	 * @return {AttributeNode} A reference to this node.
	 */
	setAttributeName( attributeName ) {

		this._attributeName = attributeName;

		return this;

	}

	/**
	 * Returns the attribute name of this node. The method can be
	 * overwritten in derived classes if the final name must be computed
	 * analytically.
	 *
	 * @param {NodeBuilder} builder - The current node builder.
	 * @return {string} The attribute name.
	 */
	getAttributeName( /*builder*/ ) {

		return this._attributeName;

	}

	generate( builder ) {

		const attributeName = this.getAttributeName( builder );
		const nodeType = this.getNodeType( builder );
		const geometryAttribute = builder.hasGeometryAttribute( attributeName );

		if ( geometryAttribute === true ) {

			const attribute = builder.geometry.getAttribute( attributeName );
			const attributeType = builder.getTypeFromAttribute( attribute );

			const nodeAttribute = builder.getAttribute( attributeName, attributeType );

			if ( builder.shaderStage === 'vertex' ) {

				return builder.format( nodeAttribute.name, attributeType, nodeType );

			} else {

				const nodeVarying = varying( this );

				return nodeVarying.build( builder, nodeType );

			}

		} else {

			warn( `AttributeNode: Vertex attribute "${ attributeName }" not found on geometry.` );

			return builder.generateConst( nodeType );

		}

	}

	serialize( data ) {

		super.serialize( data );

		data.global = this.global;
		data._attributeName = this._attributeName;

	}

	deserialize( data ) {

		super.deserialize( data );

		this.global = data.global;
		this._attributeName = data._attributeName;

	}

}

export default AttributeNode;

/**
 * TSL function for creating an attribute node.
 *
 * @tsl
 * @function
 * @param {string} name - The name of the attribute.
 * @param {?string} [nodeType=null] - The node type.
 * @returns {AttributeNode}
 */
export const attribute = ( name, nodeType = null ) => new AttributeNode( name, nodeType );